JP2009083329A - Thermal transfer image receiving sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal transfer image receiving sheet which is highly efficiently manufactured by simultaneously forming a plurality of layers on a substrate sheet and is excellent in printing sensitivity. <P>SOLUTION: The thermal transfer image receiving sheet is equipped with: a substrate sheet; a porous layer formed on the substrate sheet and containing hollow particles; and a receiving layer formed on the porous layer and comprising a receiving layer forming resin with dye dyable properties, and polyvinyl alcohol and a tetraboric acid compound are incorporated in the porous layer. The above problem is solved by providing the thermal transfer image receiving sheet. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermal transfer image receiving sheet used for printing by a sublimation thermal transfer system.

  As a method of forming an image using thermal transfer, a thermal transfer sheet in which a thermal diffusion dye (sublimation dye) as a recording material is carried on a base sheet such as a plastic film, and another base such as paper or plastic film A thermal diffusion transfer system (sublimation thermal transfer system) is known in which a thermal transfer image receiving sheet provided with a receiving layer on a sheet is superposed on each other to form a full color image. Since this method uses a thermal diffusion dye as a color material, the density and gradation can be freely adjusted in dot units, and a full-color image exactly as the original can be clearly displayed on the image-receiving sheet. It is applied to color image formation for computers and the like. The image is of a high quality comparable to a silver salt photograph.

  The thermal transfer image-receiving sheet has a configuration in which a plurality of layers are laminated on a base material sheet. As a method for producing such a thermal transfer image-receiving sheet, for example, by gravure coating or the like, A method of sequentially forming a porous layer and a receiving layer is known. However, since this method is a method of sequentially forming each layer, there is a problem that the number of steps increases. Therefore, in order to obtain a thermal transfer image-receiving sheet with a smaller number of steps, for example, using a slide coating method or the like that applies the coating liquid constituting each layer on the base sheet while being stacked one above the other on the base sheet. At the same time, a method of forming a plurality of layers simultaneously has attracted attention (for example, Patent Documents 1 to 3).

  The method for producing a thermal transfer image-receiving sheet by forming a plurality of layers at the same time has a very advantageous aspect in terms of production efficiency and production cost, but on the other hand, it is possible to form each layer uniformly without mixing them. There is a problem that it is difficult. For example, in the above-described slide coating method, if the viscosity and surface tension of each coating solution are not appropriate, mixing and repelling occur between the coating solutions, and the film thickness of each layer cannot be kept uniform. There was a problem. Such a problem increases as the number of layers formed simultaneously increases.

  In order to solve such a problem, Patent Document 1 discloses that a gelling agent such as gelatin, pectin, agar, carrageenan, gellan gum or the like is used to simultaneously form a plurality of layers on a base sheet using a slide coating method. Is added to the coating liquid for forming each layer, and after the coating liquid is applied to the substrate sheet, the coating film is cooled and set at a low temperature, thereby preventing each layer from mixing. Yes. Certainly, such a method is useful in that it is easy to form a uniformly laminated coating film without mixing each layer due to the effect of improving the viscosity of each layer by the gelling agent. However, at the present time when improvement in the productivity of thermal transfer image-receiving sheets is demanded, the gelling agents described above have insufficient gelling properties, and if a plurality of layers are formed at the same time, the layers may be mixed. There was a problem that it was expensive.

JP 2006-88691 A JP-A-6-171240 JP 2006-103040 A

  The present invention has been made in view of such problems, and a thermal transfer image-receiving sheet that can be produced with high efficiency by simultaneously forming a plurality of layers on a substrate sheet and that has excellent printing sensitivity. The main purpose is to provide.

  In order to solve the above problems, the present invention provides a base sheet, a porous layer formed on the base sheet and containing hollow particles, and formed on the porous layer, and has dye-dyeing properties. There is provided a thermal transfer image receiving sheet comprising a receiving layer containing a receiving layer forming resin, wherein the porous layer contains polyvinyl alcohol and a tetraborate compound.

According to the present invention, when the porous layer contains polyvinyl alcohol and a tetraboric acid compound, the tetraboric acid compound forms a hydrogen bond with the hydroxyl group of the polyvinyl alcohol, whereby By cross-linking polyvinyl alcohol between molecules starting from an acid compound, it is possible to impart excellent gelling properties to the polyvinyl alcohol. For this reason, according to the present invention, after applying a plurality of layers including a porous layer on a substrate sheet at the same time, the polyvinyl alcohol is gelled by cooling treatment, whereby the plurality of layers are simultaneously formed into each layer. Can be formed uniformly without being mixed with each other.
For this reason, according to the present invention, it is possible to obtain a thermal transfer image-receiving sheet that can be produced with high efficiency by simultaneously forming a plurality of layers on a substrate sheet and that has excellent printing sensitivity.

  In the present invention, the receiving layer forming resin is preferably an aqueous resin that can be dispersed and dissolved in an aqueous solvent, and the receiving layer preferably contains a cooling gelling agent. When the thermal transfer image-receiving sheet of the present invention is produced by using the aqueous resin as the receptor layer-forming resin, the porous layer and the receptor layer are simultaneously formed on the substrate sheet using only an aqueous solvent. This is because it can be applied. In addition, when the thermal transfer image receiving sheet of the present invention is produced by simultaneously applying the receiving layer and the porous layer on the base sheet by including a cooling gelling agent in the receiving layer. This is because the receiving layer and the porous layer can be prevented from mixing with each other.

  Furthermore, in this invention, it is preferable that the undercoat layer which improves the adhesiveness of the said base material sheet and the said porous layer is formed between the said base material sheet and the said porous layer. Moreover, it is preferable that the primer layer which improves the adhesiveness of the said porous layer and the said receiving layer is formed between the said porous layer and the said receiving layer. This is because the formation of these layers enables the thermal transfer image-receiving sheet of the present invention to have excellent adhesion between the layers.

  The thermal transfer image-receiving sheet of the present invention can be produced with high efficiency by simultaneously forming a plurality of layers on a substrate sheet, and has an effect of excellent printing sensitivity.

  Hereinafter, the thermal transfer image receiving sheet of the present invention will be described.

  As described above, the thermal transfer image-receiving sheet of the present invention is formed on the base sheet, the porous layer formed on the base sheet and containing the hollow particles, and formed on the porous layer. A receiving layer containing a receiving layer-forming resin, wherein the porous layer contains polyvinyl alcohol and a tetraborate compound.

Such a thermal transfer image receiving sheet of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing an example of the thermal transfer image receiving sheet of the present invention. As illustrated in FIG. 1, a thermal transfer image-receiving sheet 10 of the present invention includes a base sheet 1, a porous layer 2 formed on the base sheet 1 and containing hollow particles, and the porous layer 2. And a receiving layer 3 containing a receiving layer-forming resin having dye-dyeing properties.
In such an example, the thermal transfer image-receiving sheet of the present invention is characterized in that the porous layer 2 contains polyvinyl alcohol and a tetraborate compound.

According to the present invention, when the porous layer contains polyvinyl alcohol and a tetraboric acid compound, the tetraboric acid compound forms a hydrogen bond with the hydroxyl group of the polyvinyl alcohol, whereby By cross-linking polyvinyl alcohol between molecules starting from an acid compound, it is possible to impart excellent gelling properties to the polyvinyl alcohol. For this reason, according to the present invention, after applying a plurality of layers including a porous layer on a substrate sheet at the same time, the polyvinyl alcohol is gelled by cooling treatment, whereby the plurality of layers are simultaneously formed into each layer. Can be formed uniformly without being mixed with each other.
For this reason, according to the present invention, it is possible to obtain a thermal transfer image-receiving sheet that can be produced with high efficiency by simultaneously forming a plurality of layers on a substrate sheet and that has excellent printing sensitivity.

Here, it can be considered that the above-described excellent gelling properties can be imparted to polyvinyl alcohol by using it together with the tetraboric acid compound for the following reason.
That is, polyvinyl alcohol is a polymer material having a plurality of hydroxyl groups in the molecule, and the hydroxyl groups are rich in hydrogen bond formation.
On the other hand, the tetraborate compound has a structure in which metal ions are bonded to tetraborate ions having four hydroxyl groups in the molecule.
Therefore, by using the tetraborate compound and the polyvinyl alcohol in combination, a high-density hydrogen bond represented by the following formula between the hydroxyl group of the polyvinyl alcohol and the hydroxyl group of the tetraborate ion: Can be formed. For this reason, when the tetraborate compound and the polyvinyl alcohol are used in combination, the polyvinyl alcohol can be intermolecularly cross-linked by the hydrogen bond network starting from the tetraborate ion. Excellent gelling properties can be imparted.

  In addition, compared with gelatin, which is often used as a cooling gelling agent in general, polyvinyl alcohol gels quickly at room temperature, and thus has an advantage that the cooling time in the cooling step can be shortened. Moreover, it is possible to make it gelatinize at normal temperature, without cooling.

The thermal transfer image receiving sheet of the present invention has at least a base sheet, a porous layer, and a receiving layer, and may have any other configuration as necessary.
Hereafter, each structure used for this invention is demonstrated in order.

1. Porous layer First, the porous layer used in the present invention will be described. The porous layer used in the present invention is formed on a substrate sheet, contains hollow particles, and is added from the thermal head to the receiving layer when forming an image using the thermal transfer image receiving sheet of the present invention. It has a heat insulating property to prevent the generated heat from being lost by transferring heat to the base sheet or the like. And the porous layer used for this invention is characterized by including polyvinyl alcohol and a tetraborate compound.
Hereinafter, such a porous layer will be described in detail.

(1) Polyvinyl alcohol First, the polyvinyl alcohol used for this invention is demonstrated. The polyvinyl alcohol used in the present invention is contained together with the tetraborate compound described later in the porous layer forming coating solution used for forming the porous layer when the thermal transfer image-receiving sheet of the present invention is produced. By this, it will not specifically limit if the viscosity characteristic of the said coating liquid can be adjusted to a predetermined range.

  Examples of the polyvinyl alcohol used in the present invention include known fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, or modified polyvinyl alcohol obtained by modifying some hydroxyl groups of polyvinyl alcohol. In the present invention, any of these polyvinyl alcohols can be suitably used.

  In the present invention, only one type of polyvinyl alcohol may be used, or two or more types of polyvinyl alcohol may be used.

  In the present invention, the amount of polyvinyl alcohol contained in the porous layer is that of the coating liquid for forming a porous layer used for forming the porous layer when the thermal transfer image-receiving sheet of the present invention is produced. The viscosity property is not particularly limited as long as it can be adjusted within a predetermined range, but in the present invention, in the present invention, when the entire porous layer is 100, it is within the range of 1% by mass to 70% by mass. In particular, it is preferably in the range of 1% by mass to 60% by mass, and more preferably in the range of 5% by mass to 40% by mass. When the content ratio of polyvinyl alcohol is less than the above range, for example, unevenness or the like may easily occur when the receiving layer forming coating solution is applied and dried on the substrate sheet. Moreover, it is because a density | concentration may fall when there are more than the said range, for example because hollow particles decrease.

(2) Tetraborate Compound Next, the tetraborate compound used in the present invention will be described. The tetraboric acid compound used in the present invention is not particularly limited as long as it can impart gelling properties to polyvinyl alcohol by using it together with polyvinyl alcohol.
Here, the tetraborate compound used in the present invention refers to a compound having a structure in which metal ions are bonded to tetraborate ions.

The tetraborate compound used in the present invention is not particularly limited as long as it has a structure in which metal ions are bonded to tetraborate ions. Examples of such a tetraborate compound include sodium tetraborate and lithium tetraborate. Among them, sodium tetraborate is preferably used in the present invention.
The sodium tetraborate used in the present invention may be a hydrate.

  Only one type of tetraborate compound may be used in the present invention, or two or more types may be used.

  In the present invention, the amount of the tetraborate compound contained in the porous layer is particularly limited as long as it is within a range in which desired gelling properties can be imparted to polyvinyl alcohol, depending on the type of tetraborate compound. It is not something. In particular, in the present invention, the content of the tetraboric acid compound is preferably in the range of 0.01 to 40 parts by weight with respect to 100 parts by weight of polyvinyl alcohol contained in the porous layer. It is preferably in the range of 0.03 to 40 parts by weight, and more preferably in the range of 0.1 to 25 parts by weight. This is because if the content of the tetraboric acid compound is less than the above range, it may be difficult to impart desired gelling properties to the polyvinyl alcohol.

(3) Hollow particles First, the hollow particles used in the present invention will be described. The hollow particles used in the present invention have a function of imparting heat insulation to the porous layer. Moreover, the hollow particles used in the present invention have a function of imparting cushioning properties to the porous layer.

  The hollow particles used in the present invention are not particularly limited as long as desired heat insulating properties and cushioning properties can be imparted to the porous layer. Therefore, the hollow particles used in the present invention may be expanded particles or non-expanded particles. In addition, the expanded particles may be independent expanded particles or may be continuous expanded particles. Furthermore, the hollow particles used in the present invention may be organic hollow particles composed of resin or the like, or inorganic hollow particles composed of glass or the like. The hollow particles may be cross-linked hollow particles.

  Examples of the resin constituting the hollow particles include styrene resins such as crosslinked styrene-acrylic resins, (meth) acrylic resins such as acrylonitrile-acrylic resins, phenolic resins, fluorine resins, polyamide resins, and polyimide resins. Examples thereof include resins, polycarbonate resins, and polyether resins.

  The average particle diameter of the hollow particles is not particularly limited as long as the desired heat insulation and cushioning properties can be imparted to the porous layer depending on the type of resin constituting the hollow particles, etc. , Preferably in the range of 0.1 μm to 15 μm, particularly preferably in the range of 0.1 μm to 10 μm. This is because if the average particle size is too small, the amount of hollow particles used increases and the cost increases, and if the average particle size is too large, it becomes difficult to form a smooth porous layer.

  In the present invention, the amount of the hollow particles contained in the porous layer is not particularly limited as long as a porous layer having desired heat insulating properties and cushioning properties can be obtained. For example, 30% by mass to 90% by mass %, Preferably in the range of 50 to 85% by weight. This is because if the content is too small, the voids in the porous layer are reduced and sufficient heat insulating properties and cushioning properties may not be obtained. If the content is too large, the adhesiveness is inferior.

  Moreover, in this invention, the ratio of the hollow particle contained in a porous layer and polyvinyl alcohol will not be specifically limited if the porous layer which has desired heat insulation property can be formed. Especially, in this invention, it is preferable that a hollow particle exists in the range of 50-950 in weight conversion with respect to polyvinyl alcohol 100, It is preferable that it is in the range of 100-950 especially, Furthermore, 200- It is preferable to be within the range of 900. It is because the porous layer excellent in heat insulation can be formed because the content ratio of a hollow particle and polyvinyl alcohol is in the said range.

(4) Arbitrary compound Although the porous layer used for this invention contains the said polyvinyl alcohol, a tetraborate compound, and a hollow particle at least, even if it contains an arbitrary compound as needed, Good. Examples of the compound that can be contained in the porous layer as the above arbitrary compound include a binder for forming a porous layer, a surfactant such as a nonionic silicone, a curing agent such as an isocyanate compound, a wetting agent, and a dispersion. An agent etc. can be mentioned.

  As the porous layer forming binder, an aqueous resin is usually used. Examples of such water-based resins include polyurethane resins such as acrylic urethane resins, polyester resins, gelatin, polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, pullulan, carboxymethyl cellulose, hydroxyethyl cellulose, dextran, dextrin, and polyacrylic acid. And salts thereof, agar, κ-carrageenan, λ-carrageenan, ι-carrageenan, casein, xanthene gum, locust bean gum, alginic acid, gum arabic, and those described in JP-A-7-195826 and 7-9757. Homopolymerization of a real xylene oxide copolymer, water-soluble polyvinyl butyral, or a vinyl monomer having a carboxyl group or a sulfonic acid group described in JP-A-62-245260 And copolymers and the like. Moreover, you may use in combination of 2 or more types of the said resin.

(5) Porous layer In the porous layer used in the present invention, the heat applied from the thermal head to the receiving layer is transferred to the substrate sheet or the like when an image is formed using the thermal transfer image receiving sheet of the present invention. It has a heat insulating property to prevent loss due to heating. Here, the heat insulation property of the porous layer used in the present invention can be appropriately adjusted according to the use of the thermal transfer image-receiving sheet of the present invention. In addition, the heat insulation of a porous layer can be adjusted to arbitrary ranges, for example by changing the thickness of a porous layer.

The heat insulation property of the porous layer can also be controlled by the porosity of the porous layer. Here, the porosity of the porous layer used in the present invention is preferably in the range of 15% to 80%.
In addition, the said porosity shall point out the value represented by (the porosity of a hollow particle) x (the content rate of the hollow particle in a porous layer).

The thickness of the porous layer used in the present invention is preferably in the range of 10 μm to 100 μm, and more preferably in the range of 10 μm to 50 μm. The density of the porous layer, for example in the range of ^{0.1g / cm 3 ~0.8g / cm 3} , in a range of inter alia 0.2g ^/ cm ³ ~0.7g ^/ cm 3 preferable.

  The porous layer used in the present invention may have a configuration composed of a single layer, or may have a configuration in which a plurality of layers are laminated. Here, the porous layer having a configuration in which a plurality of layers are stacked may have a configuration in which layers of the same composition are stacked, or has a configuration in which layers of different compositions are stacked. It may be a thing. In particular, the porous layer used in the present invention preferably has a structure in which two layers having different compositions are laminated. It is because a more functional porous layer can be obtained by setting it as such a structure.

  As an example when the porous layer used in the present invention has a two-layer structure, the porous layer comprises, from the base sheet side, the porous layer A containing the hollow particles a, and the hollow particles a. There can also be mentioned those having a structure in which a porous layer B containing hollow particles b having a small hollow ratio is laminated. By using the porous layer having such a configuration, there is an advantage that density unevenness and white spots in highlight portions can be prevented during printing.

2. Receiving layer Next, the receiving layer used in the present invention will be described. The receiving layer used in the present invention is formed on the above-described porous layer, and includes a receiving layer forming resin having dye dyeing properties, and when the thermal transfer image receiving sheet of the present invention is printed, The dye has a function of forming an image by being dyed.
Hereinafter, such a receiving layer will be described in detail.

(1) Receiving layer forming resin First, the receiving layer forming resin will be described. The receptor layer forming resin used in the present invention is not particularly limited as long as it has dye-dyeing properties. Among them, the receiving layer forming resin used in the present invention preferably has a glass transition temperature of 20 ° C. or higher, more preferably 30 ° C. or higher, and further preferably 40 ° C. or higher. The receptor layer-forming resin preferably has a glass transition temperature of 120 ° C. or lower. This is because by using a receiving layer forming resin having a glass transition temperature in such a range, a thermal transfer image receiving sheet having particularly excellent heat resistance can be obtained.

  The receptor layer-forming resin used in the present invention may be a solvent-based resin that can be dispersed and dissolved in an organic solvent, or an aqueous resin that can be dispersed and dissolved in an aqueous solvent. In the present invention, an aqueous resin is preferable. When the thermal transfer image-receiving sheet of the present invention is produced by using the aqueous resin as the receptor layer-forming resin, the porous layer and the receptor layer are simultaneously formed on the substrate sheet using only an aqueous solvent. This is because it can be applied.

  Here, the “aqueous solvent” refers to a solvent containing water as a main component. The ratio of water in the aqueous solvent is usually 60% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more. Examples of solvents other than water include alcohols such as methanol, ethanol, isopropanol, and n-propanol; glycols such as ethylene glycol, diethylene glycol, and glycerin; esters such as ethyl acetate and propyl acetate; ketones such as acetone and methyl ethyl ketone. Amides such as N, N-dimethylformamide can be exemplified.

  The aqueous resin is not particularly limited as long as it can disperse and dissolve a predetermined amount in a desired aqueous solvent. Examples of such aqueous resins include polyolefin resins, polyvinyl resins, polyester resins, polyurethane resins, polycarbonate resins, polyamide resins, poly (meth) acrylic acid resins, cellulose derivative resins, or polyether resins. Etc. In the present invention, any of these water-based resins can be suitably used, and among these, polyvinyl resins are preferably used.

  Examples of the polyvinyl resin suitably used in the present invention include a vinyl chloride / vinyl acetate copolymer, a vinyl chloride / acrylic compound copolymer, an ethylene / vinyl chloride / acrylic ester copolymer, and an ethylene / vinyl acetate. / Vinyl chloride copolymer.

  The vinyl chloride / vinyl acetate copolymer is not particularly limited as long as it is a copolymer composed of vinyl chloride and vinyl acetate, and can be copolymerized with these essential monomers in addition to vinyl chloride and vinyl acetate. The body may be obtained by polymerizing a small amount.

The vinyl chloride / acrylic compound copolymer is not particularly limited as long as it is a copolymer composed of vinyl chloride and an acrylic compound, and a single amount copolymerizable with these essential monomers in addition to vinyl chloride and an acrylic compound. The body may be obtained by copolymerization in a small amount.
In the present specification, “acrylic compound” means (meth) acrylic acid and / or an alkyl ester thereof.

  Examples of the acrylic compound include acrylic acid; acrylic acid salts such as calcium acrylate, zinc acrylate, magnesium acrylate, and aluminum acrylate; methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and 2-ethoxyethyl. Acrylates such as acrylate, 2-hydroxyethyl acrylate, n-stearyl acrylate, tetrahydrofurfuryl acrylate, trimethylolpropane triacrylate; methacrylic acid; methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, tridecyl methacrylate, Cyclohexyl methacrylate, triethylene glycol dimethacrylate, 1,3-butylene dimethacrylate, trimethylol trimethacrylate It can be mentioned methacrylic acid esters of bread, etc., and the like.

  The ethylene / vinyl chloride / acrylic acid ester copolymer and the ethylene / vinyl acetate / vinyl chloride copolymer (hereinafter, these copolymers are collectively referred to as “ethylene / vinyl chloride copolymer”). Is not particularly limited as long as it is a copolymer obtained by polymerizing at least three monomers of ethylene, vinyl chloride and acrylate, or three monomers of ethylene, vinyl acetate and vinyl chloride. In addition to these three types of monomers, a small amount of a small amount of monomer may be copolymerized.

  The ethylene / vinyl acetate / vinyl chloride copolymer may be a copolymer of ethylene / vinyl acetate copolymer (EVA) and vinyl chloride. As the EVA / vinyl chloride copolymer, EVA may be used. It may be a graft copolymerized vinyl chloride. EVA includes those in which all or part of vinyl acetate units in the copolymer is saponified.

  In the present invention, “acrylic acid ester” constituting the ethylene / vinyl chloride / acrylic acid ester copolymer is a concept including a methacrylic acid ester in addition to the acrylic acid ester. Examples of the acrylic acid ester include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-ethoxyethyl acrylate, 2-hydroxyethyl acrylate, n-stearyl acrylate, tetrahydrofurfuryl acrylate, and trimethylolpropane triacrylate. Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, tridecyl methacrylate, cyclohexyl methacrylate, triethylene glycol dimethacrylate, dimethacrylic acid-1, Examples include 3-butylene and trimethylolpropane trimethacrylate.

  In the present invention, only one type of the receiving layer forming resin may be used, or two or more types having different monomer compositions, average molecular weights, and the like may be used.

(2) Arbitrary Compound The receptor layer used in the present invention contains at least the above-mentioned receptor layer forming resin, but may contain other optional compounds as necessary. Especially, in this invention, it is preferable to use a cooling gelling agent as said arbitrary compound. As described above, the porous layer used in the present invention contains polyvinyl alcohol and a tetraborate compound, so that when the thermal transfer image receiving sheet of the present invention is formed, a plurality of layers including the porous layer are simultaneously formed. Even if it is formed, the porous layer and other layers can be prevented from mixing, but the receiving layer also contains a cooling gelling agent, so that the porous layer and the receiving layer are separated. It is because it becomes easy to form simultaneously.

  The cooling gelling agent used in the present invention has a property of gelling when cooled, and is particularly limited as long as it can give the above-described viscosity characteristics to the coating liquid for forming a porous layer. Is not to be done. Among them, the cooling gelling agent used in the present invention is preferably one having a viscosity at 15 ° C. of 3 times or more, particularly 5 times or more, more preferably 10 times or more of the viscosity at 80 ° C.

  Examples of such a cooling gelling agent include gelatin, polyvinyl alcohol, agar, κ-carrageenan, λ-carrageenan, ι-carrageenan, pectin and the like.

  Here, the gelatin is composed of a peptide chain obtained by denaturing collagen having a triple helix structure as described above, and partially recovers the triple helix structure by cooling, By forming a three-dimensional network starting from the recovered triple helix structure, it exhibits cooling gelation characteristics.

  The above-mentioned κ-carrageenan, λ-carrageenan, and ι-carrageenan are natural polymer compounds mainly composed of galactose and 3,6-anhydrogalactose having a molecular weight of about 100,000 to 500,000 extracted from red algae seaweed. It is characterized by having a half-ester type sulfate group in the molecule, and usually exhibits a gelling property by using a thickener such as locust bean gum or a metal salt compound in combination. is there.

  The pectin is a natural polysaccharide that constitutes a cell wall of a plant, and exhibits cooling gelation characteristics when used in combination with an ionic compound.

  In the present invention, any of the above cooling gelling agents can be suitably used. In the present invention, only one type of cooling gelling agent may be used, or two or more types of cooling gelling agent may be used.

  When the above-mentioned cooling gelling agent is contained in the receiving layer, the content of the cooling gelling agent in the receiving layer is the formation of the receiving layer used to form the receiving layer when the thermal transfer image-receiving sheet of the present invention is produced. There is no particular limitation as long as the desired viscosity characteristics can be imparted to the coating liquid. In particular, in the present invention, the cooling gelling agent is preferably within a range of 1 to 100, particularly preferably within a range of 1 to 40, in terms of weight with respect to the receiving layer forming resin 100. Furthermore, it is preferable to be within the range of 2-40. If the content ratio of the cooling gelling agent is less than the above range, for example, unevenness or the like may easily occur when the receiving layer forming coating solution is applied and dried on the base sheet. is there. Further, if the amount is larger than the above range, for example, dyeing may be hindered during image formation, and the density may decrease.

In addition to the cooling gelling agent, examples of optional compounds that can be added to the receptor layer include mold release agents, antioxidants, ultraviolet absorbers, light stabilizers, fillers, pigments, antistatic agents, and plasticizers. And a hot-melt material.
Examples of the release agent include known ones such as silicone oil, phosphate ester compounds, and fluorine compounds, and silicone oil is particularly preferable.
Examples of the silicone oil include epoxy-modified silicone oil, alkyl-modified silicone oil, amino-modified silicone oil, fluorine-modified silicone oil, phenyl-modified silicone oil, polyether-modified silicone oil, vinyl-modified silicone oil, and hydrogen-modified silicone oil. Silicone oil is preferred. Emulsified silicone may also be used. The release agent is preferably added so as to be in the range of 0.5 to 30 parts by mass with respect to 100 parts by mass of the above-described receptor layer forming resin.

(3) Receptor Layer The thickness of the receptor layer used in the present invention is not particularly limited as long as it is within a range in which a desired printing sensitivity can be expressed according to the type of the resin for forming the receptor layer. In the present invention, it is preferably in the range of 0.5 μm to 30 μm, particularly preferably in the range of 0.5 μm to 20 μm, and more preferably in the range of 1 μm to 15 μm.

3. Next, the base sheet used in the present invention will be described. The base sheet used in the present invention has a function of supporting the porous layer and the receiving layer described above.
Hereinafter, such a base sheet will be described.

  The substrate sheet used in the present invention is not particularly limited as long as it has a desired heat resistance depending on the printing temperature when forming an image using the thermal transfer image-receiving sheet of the present invention. However, specific examples include resin-coated paper, resin film base, and paper base. Among them, resin-coated paper is preferable.

  Resin-coated paper is usually formed by laminating a base resin layer on both sides of a base paper. Examples of the base paper constituting the base paper include natural pulp, synthetic pulp, and pulp paper made from a mixture thereof. Among these, it is preferable to use paper mainly composed of wood pulp. The base paper may be subjected to a conventionally known process such as a calendar process to be described later if necessary.

  The base paper preferably has a thickness in the range of 10 μm to 1000 μm, and more preferably in the range of 50 μm to 300 μm.

  The base paper can be produced by a known method, but a base paper that is calendered is preferable. This is because when a base paper that has been calendered is used for the base paper, the smoothness can be improved and the glossiness of the resulting thermal transfer image-receiving sheet can be enhanced.

  The resin for forming the base resin layer is preferably a resin having a small neck-in and a good drawdown property. For example, a polyolefin resin, a polystyrene resin, a vinyl resin, a polyester resin, an ionomer Resin, nylon, polyurethane and the like can be mentioned, and a polyolefin resin is preferable in that a film excellent in water resistance, strength, gloss and the like can be obtained.

  Examples of the polyolefin resin include high-density polyethylene, medium-density polyethylene, low-density polyethylene, polypropylene, polybutene, and polypentene. Among these, high-density polyethylene, medium-density polyethylene, low-density polyethylene, and polypropylene are preferable, and polypropylene is particularly preferable. Is preferred.

  The base resin layer may be a film or sheet obtained by mixing one or more of the resins, or a film or sheet formed by adding a pigment, a filler or the like to the resin. It may be. Further, the resin may be one obtained by blending an additive such as a modifier to improve adhesiveness. Examples of the modifier include olefin copolymers such as Tuffmer (manufactured by Mitsui Chemicals).

  The resin-coated paper can be produced by a known laminating method such as dry lamination, wet lamination, or extrusion. Each of the above layers can be appropriately subjected to primer treatment or corona discharge treatment for the purpose of improving interlayer adhesion.

  The total thickness of the resin-coated paper is, for example, preferably in the range of 10 μm to 1000 μm, and more preferably in the range of 50 μm to 300 μm.

  On the other hand, examples of the resin film substrate used in the present invention include polyester, polyacrylate, polycarbonate, polyurethane, polyimide, polyetherimide, cellulose derivative, polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polystyrene, and acrylic. , Polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulfone, polyether sulfone, tetrafluoroethylene, perfluoroalkyl vinyl ether, polyvinyl fluoride, tetrafluoroethylene-ethylene, tetrafluoro Examples thereof include ethylene-hexafluoropropylene, polychlorotrifluoroethylene, polyvinylidene fluoride, and the like. Among these, in the present invention, polyethylene terephthalate and polypropylene resin can be preferably used.

  The thickness of the resin film substrate is preferably, for example, in the range of 20 μm to 100 μm, more preferably in the range of 25 μm to 60 μm, and particularly preferably in the range of 30 μm to 50 μm.

  Examples of the paper substrate used in the present invention include condenser paper, glassine paper, sulfuric acid paper, or high-size paper, synthetic paper (polyolefin-based, polystyrene-based), high-quality paper, art paper, coated paper, Examples thereof include cast-coated paper, wallpaper, backing paper, synthetic resin or emulsion-impregnated paper, synthetic rubber latex-impregnated paper, synthetic resin-added paper, paperboard, and cellulose fiber paper.

  The thickness of the paper substrate is preferably, for example, in the range of 80 μm to 200 μm, in particular in the range of 100 μm to 180 μm, particularly in the range of 120 μm to 160 μm.

4). Arbitrary Configuration The thermal transfer image-receiving sheet of the present invention has at least the above-mentioned base sheet, a porous layer, and a receiving layer, but may have other arbitrary configurations as necessary. . As such other configurations, for example, an undercoat layer that is formed between the base sheet and the porous layer and improves the adhesion between the base sheet and the porous layer, and the above A primer layer that is formed between the porous layer and the receiving layer and improves the adhesion between the porous layer and the receiving layer can be exemplified. This is because, when the thermal transfer image-receiving sheet of the present invention has these layers, it can be made excellent in adhesiveness of each layer.
Hereinafter, each of these layers used in the present invention will be described in order.

(2) Undercoat layer Next, the undercoat layer will be described. The undercoat layer used in the present invention is formed between the base sheet and the porous layer or receiving layer, and has a function of improving the adhesion between the base sheet and the porous layer. is there.

  The case where the thermal transfer image-receiving sheet of the present invention has the undercoat layer will be described with reference to the drawings. FIG. 3 is a schematic view showing an example of the case where the thermal transfer image-receiving sheet of the present invention has the undercoat layer. As illustrated in FIG. 3, the thermal transfer image receiving sheet 10 of the present invention includes a base sheet 1, a porous layer 3 formed on the base sheet 1, and a receptor formed on the porous layer 3. A layer 2 and an undercoat layer 4 formed between the substrate sheet 1 and the porous layer 3 and improving the adhesion between the substrate sheet 1 and the porous layer 3. There may be.

The undercoat layer used in the present invention is not particularly limited as long as the adhesion between the substrate sheet and the porous layer can be improved to a desired level. In particular, in the present invention, it is preferable to use a resin containing an undercoat layer-forming resin that is dispersed and dissolved in an aqueous solvent.
Here, as the resin for forming the undercoat layer, the same resin as the water-based resin used as the binder for forming the porous layer described in the section “(1) Porous layer” can be used.

The undercoat layer used in the present invention preferably contains a cooling gelling agent. By including a cooling gelling agent in the undercoat layer, it is easy to simultaneously apply the undercoat layer, the porous layer and the receiving layer on the base sheet when producing the thermal transfer image-receiving sheet of the present invention. Because it becomes.
Here, the cooling gelling agent is the same as that described in the section “1. Receiving layer”, and the description thereof is omitted here.

  As the undercoat layer, when using the undercoat layer forming resin and the cooling gelling agent, the ratio of the undercoat layer forming resin in the undercoat layer and the cooling gelling agent is as follows: When forming the undercoat layer, there is no particular limitation as long as it is within a range in which desired viscosity characteristics can be imparted to the undercoat layer forming coating solution. In particular, in the present invention, the cooling gelling agent is preferably in the range of 1 to 100 in terms of weight, particularly 20 to 80, assuming that the solid content in the coating liquid for forming the undercoat layer is 100. Is preferably within the range of 25 to 75. If the content ratio of the cooling gelling agent is less than the above range, for example, unevenness or the like may easily occur when the receiving layer forming coating solution is applied and dried on the base sheet. is there. Moreover, it is because the adhesiveness with another layer may fall, for example, when it exceeds the said range.

  The undercoat layer used in the present invention includes, for example, a nonionic silicone-based surfactant, a curing agent such as an isocyanate compound, a wetting material, in addition to the above-described undercoat layer-forming resin and the above cooling gelling agent. And dispersants. The curing agent is particularly effective when, for example, a thermoplastic resin having active hydrogen is used as the undercoat layer forming resin.

(3) Primer layer Next, the primer layer used in the present invention will be described. The primer layer used in the present invention is formed between the porous layer and the receiving layer, and has a function of improving the adhesion between the porous layer and the receiving layer.

  The case where the thermal transfer image receiving sheet of the present invention has the primer layer will be described with reference to the drawings. FIG. 4 is a schematic view showing an example in which the thermal transfer image-receiving sheet of the present invention has the primer layer. As illustrated in FIG. 4, the thermal transfer image receiving sheet 10 of the present invention includes a base sheet 1, a porous layer 3 formed on the base sheet 1, and a receiving layer formed on the porous layer 3. 2, an undercoat layer 4 that is formed between the base sheet 1 and the porous layer 3 and improves the adhesion between the base sheet 1 and the porous layer 3, and the porous layer 3. And a primer layer 5 which is formed between the porous layer 3 and the receiving layer 2 and is formed between the receiving layer 2 and the receiving layer 2.

The primer layer used in the present invention is not particularly limited as long as it has predetermined properties. Among these, the primer layer used in the present invention preferably contains a primer layer forming resin that can be dispersed and dissolved in an aqueous solvent.
Here, as the primer layer forming resin, the same resin as the water-based resin used as the porous layer forming binder described in the section of “(1) Porous layer” can be used.

The primer layer used in the present invention preferably contains a cooling gelling agent. By including a cooling gelling agent in the undercoat layer, it is easy to simultaneously apply the undercoat layer, the porous layer and the receiving layer on the base sheet when producing the thermal transfer image-receiving sheet of the present invention. Because it becomes.
Here, the cooling gelling agent is the same as that described in the section “1. Receiving layer”, and the description thereof is omitted here.

  In the case of using the primer layer forming resin and the cooling gelling agent as the primer layer, the ratio of the primer layer forming resin and the cooling gelling agent in the primer layer In forming the primer layer, the primer layer forming coating solution is not particularly limited as long as the desired viscosity characteristics can be imparted to the primer layer forming coating solution. In particular, in the present invention, the cooling gelling agent is in the range of 1 to 100 in terms of weight when the solid content in the primer layer forming coating solution is 100 in terms of weight relative to the primer layer forming resin. Is preferably within the range of 3 to 80, more preferably within the range of 5 to 75. If the content ratio of the cooling gelling agent is less than the above range, for example, unevenness or the like may easily occur when the receiving layer forming coating solution is applied and dried on the base sheet. is there. Moreover, it is because the adhesiveness with another layer may fall, for example, when it exceeds the said range.

  In addition to the primer layer forming resin and the cooling gelling agent, the primer layer used in the present invention includes, for example, a nonionic silicone surfactant, a curing agent such as an isocyanate compound, a wetting agent, and the like. Further, a dispersant or the like may be contained.

5). Method for Manufacturing Thermal Transfer Image Receiving Sheet Next, a method for manufacturing the thermal transfer image receiving sheet of the present invention will be described. The thermal transfer image receiving sheet of the present invention can be generally produced using a method known as a method for producing a thermal transfer image receiving sheet. Among them, the method for producing the thermal transfer image-receiving sheet of the present invention includes a coating solution for forming a porous layer in which hollow particles, polyvinyl alcohol and a tetraborate compound are dispersed and dissolved in an aqueous solvent, a resin for forming a receiving layer, and a cooling gel. Using a coating solution for forming a receiving layer in which an agent is dispersed and dissolved in an aqueous solvent, the coating solution for forming a porous layer and a coating solution for forming a receiving layer are formed on a base sheet by a slide coating method. Can be produced with high efficiency by a method using a simultaneous multilayer coating step in which the coating film formed on the base sheet is cooled by the simultaneous multilayer coating step.

  For example, as shown in FIG. 4, the slide coating method suitably used for the multi-layer simultaneous application step is a state in which a plurality of coating liquids 11 to 13 constituting each layer of the thermal transfer image receiving sheet are stacked in the vertical direction, This is a method of applying to the base material sheet 15 wound around the back roll 14. From the viewpoint of coating quality, the slide coating method is excellent in film thickness uniformity, and since there is no rotating part, quality defects due to scattering of the coating liquid are unlikely to occur, and there is no friction part, so there is no friction part. There is an advantage that loss due to cutting is less likely to occur. Also, from the viewpoint of handling properties of the coating liquid, the slide coating method can use a coating liquid that is less likely to change in concentration, viscosity, and composition of the coating liquid and that has high reactivity and changes over time. The coating liquid can be used up and waste is hardly generated, and a high solid content coating liquid can be used, and the amount of solvent used can be reduced.

  In the above slide coating method, the difference in surface tension between the two coating liquids is usually within a certain range so that the porous layer forming coating liquid and the receiving layer forming coating liquid are not mixed with each other. It is adjusted to become.

  In the simultaneous multi-layer coating step, the temperature of the coating solution when applying each coating solution on the substrate sheet is usually in the range of 40 ° C to 80 ° C.

  In the cooling treatment step, as a method for cooling the coating film formed on the base sheet, for example, a method for applying the coating film on the cooled base sheet, a roll for transporting the base sheet The surface of the substrate was cooled, the method for cooling the coating film via the substrate sheet, the method for spraying cold air on the coating film, and the substrate sheet on which the coating film was formed were adjusted to room temperature below the desired temperature. A method of passing through the cooling zone is used. Since the method of applying the coating film onto the cooled substrate sheet can forcibly cool the coating film immediately after the coating film is applied onto the substrate sheet, the multilayer coating film Can be prevented from mixing.

  In the cooling treatment step, the temperature for forcibly cooling the coating film is usually in the range of 0 ° C. to room temperature.

  In addition to the production method described above, the thermal transfer image-receiving sheet of the present invention is formed on the porous layer separately after, for example, simultaneously forming a plurality of layers including a porous layer on a substrate sheet by a slide coating method. It can also be produced by a method of forming a receiving layer on the substrate.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

  Hereinafter, the present invention will be specifically described with reference to examples. The indicated parts by weight were described as solid parts by weight and diluted with pure water as necessary.

1. Example A 150 μm thick synthetic paper (manufactured by Oji Yuka: YUPO-FPG150) was used as a base sheet, the porous layer forming coating solution 1 was heated to 70 ° C., and slide coating was used to dry the thickness. Was applied at 15 g / m ² , allowed to gel at room temperature for 1 minute, and dried at 50 ° C. for 10 minutes. Thereafter, on the formed porous layer, a receiving layer-forming coating solution having the following composition was applied with a wire bar so that the thickness when dried was 4 g / m ^2, and at 110 ° C. for 1 minute. It dried and the thermal transfer image receiving sheet 1 was obtained.

(Porous layer forming coating solution 1)
Polyvinyl alcohol (PVA235, manufactured by Kuraray Co., Ltd.) 90 parts by weight Sodium tetraborate decahydrate (manufactured by Nippon Pure Chemicals) 10 parts by weight Hollow particles (SN-1055, manufactured by Rohm and Haas) 810 parts by weight Surfactant (Surfinol 440, manufactured by Nissin Chemical Industry Co., Ltd.) 0.15 parts by weight

(Receptive layer forming coating solution)
-20 parts by weight of vinyl chloride resin (Solvine C, manufactured by Nissin Chemical Industry Co., Ltd.)-2 parts by weight of silicone (X-22-3000T, manufactured by Shin-Etsu Chemical Co., Ltd.)-40 parts by weight of methyl ethyl ketone-40 parts by weight of toluene

2. Comparative Example A thermal transfer image receiving sheet 2 was obtained in the same manner as the thermal transfer image receiving sheet 1 except that the porous layer forming coating solution 1 was changed to the porous layer forming coating solution 2. The thermal transfer image-receiving sheet 2 had vertical streaks on the surface due to wind when the heat-insulating layer was dried.

(Porous layer forming coating solution 2)
Gelatin (RR, manufactured by Nitta Gelatin) 20 parts by weight Hollow particles (SN-1055, manufactured by Rohm and Haas) 80 parts by weight Surfactant (Surfinol 440, manufactured by Nissin Chemical Industry) 0.15 Parts by weight

3. Evaluation The print density was measured for the thermal transfer image-receiving sheets prepared in Examples and Comparative Examples. In the measurement, a solid black image was formed on each thermal transfer image-receiving sheet with a sublimation thermal transfer printer CP-720 (manufactured by Canon Inc.), and the optical reflection density was measured with an optical densitometer (spectrolino manufactured by Gretag Macbeth). As a result, the reflection density of the thermal transfer image receiving sheet 1 produced in the example was 2.01, while the reflection density of the thermal transfer image receiving sheet 2 produced in the comparative example was 1.95.

  In addition, in the sample shown in the comparative example, since gelatin having low gelation performance at room temperature was used when the porous layer was dried, the image quality was affected. Since gelation tends to proceed at room temperature, there was no effect on image quality.

  As described above, a thermal transfer image-receiving sheet comprising a porous layer containing hollow particles and a receiving layer formed on the porous layer and containing a receiving layer-forming resin having dye-dyeing properties. By providing polyvinyl alcohol and a tetraboric acid compound in the porous layer, a thermal transfer image-receiving sheet that can be produced with high efficiency by simultaneously forming a plurality of layers and has excellent printing sensitivity is provided. be able to.

It is the schematic which shows an example of the thermal transfer image receiving sheet of this invention. It is the schematic which shows the other example of the thermal transfer image receiving sheet of this invention. It is the schematic which shows the other example of the thermal transfer image receiving sheet of this invention. It is explanatory drawing explaining a slide coat method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,15 ... Base material sheet 2 ... Porous layer 3 ... Receiving layer 4 ... Undercoat layer 5 ... Primer layer 10, 10 ', 10''... Thermal transfer image receiving sheet 11, 12, 13 ... Coating liquid 14 ... Back roll

Claims (4)

A base sheet;
A porous layer formed on the substrate sheet and containing hollow particles;
A thermal transfer image-receiving sheet comprising: a receptor layer containing a resin for forming a receptor layer formed on the porous layer and having dye-dyeing properties;
A thermal transfer image-receiving sheet, wherein the porous layer contains polyvinyl alcohol and a tetraborate compound.   The thermal transfer image receiving apparatus according to claim 1, wherein the receiving layer forming resin is an aqueous resin that can be dispersed and dissolved in an aqueous solvent, and the receiving layer contains a cooling gelling agent. Sheet.   The undercoat layer which improves the adhesiveness of the said base material sheet and the said porous layer is formed between the said base material sheet and the said porous layer, The Claim 1 or Claim characterized by the above-mentioned. 2. The thermal transfer image receiving sheet according to 2.   The primer layer which improves the adhesiveness of the said porous layer and the said receiving layer is formed between the said porous layer and the said receiving layer, The Claims 1-3 characterized by the above-mentioned. The thermal transfer image receiving sheet according to any one of claims.

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